1. Field of the Invention
The present invention relates to a display device, a display method and a computer program.
2. Description of the Related Art
Display devices exist in which an image displayed on a screen is perceived by a viewer as a stereoscopic image. A time division display scheme is known as a technique to cause the viewer to perceive an image displayed on this type of display device as a stereoscopic image. In the time division display scheme, an image for the left eye and an image for the right eye are alternately displayed on the entire screen at very short intervals (see JP H9-138384A, JP 2000-36969A, and JP 2003-45343A).
An image displayed using the time division display scheme can be perceived by the viewer as a stereoscopic image through shutter glasses worn by the viewer or through a parallax barrier. In case of using the shutter glasses scheme, during a period in which an image for the left eye is displayed, a left eye shutter (a liquid crystal shutter, for example) of the shutter glasses is opened to allow the light from the screen to pass through, and a right eye shutter of the shutter glasses is closed to shut off the light from the screen. On the other hand, during a period in which an image for the right eye is displayed, the left eye shutter of the shutter glasses is closed to shut off the light from the screen, and the right eye shutter of the shutter glasses is opened to allow the light from the screen to pass through.
However, with this type of display device, crosstalk may occur due to characteristics of the display device and the shutter glasses, such as an insufficient liquid crystal response speed (when a liquid crystal panel is used as a screen) and insufficient contrast of the liquid crystal shutters of the shutter glasses. Crosstalk is a phenomenon in which a part of the image for the right eye leaks in the left eye and a part of the image for the left eye leaks in the right eye.
FIG. 13 is an explanatory diagram illustrating cause of crosstalk generation, which is recognized from luminance waveform. A crosstalk occurs when luminance of an image displayed on a liquid crystal panel does not reach desired luminance during a period in which a shutter of shutter glasses is opened, resulting in picture quality degradation.
As a method to improve crosstalk, a method has been proposed in which the display panel is driven at a high speed (for example, 240 Hz), and an image for the left eye and an image for the right eye are each displayed on the screen two times repeatedly, and a shutter of the shutter glasses is opened only in a period during which each of the images is displayed for the second time. Also, a method has been proposed in which a backlight is turned on only in a period during which each of the images is displayed for the second time. Further, as method to offset an insufficient liquid crystal response speed, overdrive processing has been proposed in which an applied voltage value for each pixel of a liquid crystal panel is corrected.